This invention relates to Filler-modified Epoxy Resin Hardener Composite
Paints for Acoustic Attenuation.
BACKGROUND OF THE INVENTION:
Because of various detrimental health hazards and environmental issues
on noise pollution, mitigation in noise control measures in all public places
to homes has drawn significant attention to the scientific society.
Numerous methods presently exist for the control of noise and vibration
from simple passive barrier to damping techniques and to more
sophisticated electronic noise cancelling approaches. These could be
broadly classified into active, passive and semi-active methods. Active
control involves the use of active elements, i.e., speakers, actuators and
micro-processors to produce 'out-of-phase' signal to electronically cancel
the noise. The traditional passive control methods include the use of
absorbers, barriers, mufflers, silencers etc. Examples include in semi-
active methods are electro-rheological (ER), magneto-rheological fluids
etc. Vibration damping techniques are usually applied in close

contact with the vibrating structure to prevent or reduce air-borne or
structure-borne energy from propagating to the protected area. Both
techniques utilize internal damping of impinging acoustic energy as an
important means of reducing energy levels and therefore share basic
principles.
Within the field of noise control, absorptive techniques are typically
utilized to prevent or reduce air borne acoustic energy from reaching a
receiving site. Most sound absorptive materials are porous in structure,
such as foams, felts, etc., with the pores inter-connecting throughout the
material. The pores may be formed by inter-connected solid bubbles, or
interstices between small granules, or they may be inherent in naturally
porous fibrous materials. The amplitude of sound waves entering the
porous material is reduced through friction between the air molecules and
the surfaces of the pores. These materials are usually light in weight and
most effective at shorter wavelengths (i.e., higher frequencies), however
their structural strength is often limited.
Another approach to noise control is to utilize the "mass law", which
applies to a relatively thin, homogeneous and single layer panel. The
mass law states that the loss of energy, as it transits a barrier over a wide

frequency range, is a function of the surface density of the barrier material
and the frequency in question. By increasing the mass of the material,
thickness of the layer and density, can improve the acoustic barrier for all
frequencies including those in the lower region in the spectrum. This gain
in transmission loss is at the cost of added barrier weight.
The use of various types of filler materials in acoustic and vibration
damping is evident. Patent number US 6,872,761 B2 dated March 29,
2005 by Kevin J LeStarge et. al., used so-called expandable
microspheres in an aqueous coating composition comprised of at least
one dispersed polymer and at least one inorganic filler helps to improve
the appearance and/or sound damping properties of the coating obtained
by heating the aqueous coating composition after it has been applied to a
substrate surface.
Another report, publication number, US 2007/0048445 Al dated March 1,
2007 by Joseph DiMario et. al., describes a sound damping coating,
comprising an aqueous dispersion of polymeric micro particles prepared
from components including: (i) a functional material selected from (a) a
nitrite functional material, (b) an amide functional material, and (c) a

carbamate functional material, (ii) a polyoxyalkyfene acrylate and (iii) a
filler material.
US 2008/0028978 Al dated Feb 7, 2008 by Timothy D. Twining et. al.,
describes water-based asphalt emulsion-based coating its compositions,
manufacturing and its uses thereof, in which the coating is preferably
applied as a two-component spray comprising an aqueous catalyst and
aqueous asphalt emulsion respectively. The aqueous catalyst can employ
an aqueous acid, preferably citric acid, but can also use an aqueous
catalyst comprising an aqueous solution of calcium chloride. Preferably
each of the two components are directed through separate ports on a
spray nozzle so that they mix together on the fly external to the nozzle
before contacting the surface to be coated. This methodology can be
used to sound insulate structures, to encapsulate friable materials, to
weather coat a structure, and to create a non-corrosive waterproof
monolithic membranes.
Machineries belonging to numerous industries related to manufacturing,
automobiles, appliances, processing, operations related to grinding,
cutting, mixing, milling etc are usually composed of various metal
structures or sheets etc. Such metallic parts {particularly sheets etc) are

indeed a good source of acoustic vibrations and hence often pose
significant noise problems in industrial scenario. Various measures have
been addressed to control such noise problems.
One common example of noise reduction in automobile components
consisting metal sheets frequently have sound absorbing patches. Such
noise reduction patches include an adherent vibration dampening
material that comprises a rubbery polymeric material that is coated with a
metallic foil on one face thereof. The rubbery material is adhered to
portions of a motor vehicle body, such as the inner surfaces of door
panels, roof panels and similar areas to dampen the vibration of metallic
parts and hence noise.
Another approach of sound damping comprises dual-layered structures in
which polymers with different viscosities are stacked relationship in
layers. US patent numbers 5,227,592 by Kosters et. at., and 4,346,782 by
Bohm et. al., respectively describes this approach. Both inventions are
comprised of 'plastisol layers' based on PVC or on metbacrylates.
However, in Kosters invention, at least one of the layers is foamed,
though such patch structures suffer from limitations of adherence issues
with PVC and/or acrylic based layers which are reported not to adhere so
well on metal surfaces. Besides the foamed materials can absorb liquids,

such as processing fluids, and/ or liquids encountered in ambient storage
or use of the articles that could cause corrosion, and can interfere with
subsequent processing operations.
Other issues include relatively high glass transition temperature of the
polymers, which are also prone to cracking, de-lamination etc.
US patent number 2003/0054173 Al dated March 20, 2003 by Larry R.
Ruddy describes a spray-able coating and components that has noise
vibration and harshness reduction or absorption properties, besides
protecting from environmental hazards. The composition comprises at
least one flexible epoxy resins in amounts of 17 - 40 w%; at least one
rigid epoxy resin in amounts of 25 - 35 w% and at least one curing agent
for the epoxy resin in an amount from 2 - 6 w%. Components for which
the coating is particularly useful include automotive drive train
components requiring operation at relatively higher temperatures. Prior to
this, patent number EP 0591313B1 dated 03.04.1994 by Wilfong D. L et.
al., describes vibration-damping constructions and methods, useful for
damping vibratory and/or noise emitting structures and component parts
of devices such as automobiles, aircraft, industrial equipment, and
appliances. This vibration-damping construction comprising at least a
single layer of aromatic epoxy high temperature damping materials

Another potential approach, similar to the above, as explained in patent
number US 2009/0277716 Al, describes a composite structure containing
a so-called extension layer and rigid layer for noise damping of articles,
out of which, in some instances, the constraining layer may cover all of
the extensional layer, while in other instances, it may cover only a portion
of the extensional layer. In particular instances, the modulus of elasticity
of the constraining layer is greater than that of the modulus of elasticity of
the material comprising the extensional layer. The first polymeric material
may comprise a viscoelastic polymer. In particular instances, at least one
of the polymeric materials is a thermally curable material. In particular
instances, the thickness of the extensional layer is in the range of 1 - 6
mm, while in some particular instances, the thickness of this layer is in
the range of 2 - 4 mm with loss factor of the composite structure is
greater than 0.1 for frequencies in the range of 200 - 800 HZ. Journal of
Sound and Vibration, Volume 319, Issues 1-2, 2009, Pages 58-76
discusses the effect on noise and vibration reduction in railway vehicles
using various sheets and laminates of viscoelastic damping materials.
One disadvantage of viscoelastic polymers, while addressing
applications, is higher curing temperatures (>180°C). As the vibrating
parts of various industrial machineries could be associated

with numerous shapes, geometry and dimension etc, noise attenuation in
numerous industrial machineries, employing liquid-based polymeric
materials through a spray coating process, an ambient temperature
curing would be preferred. Besides, quite a few of the viscoelastic
polymers are reported to be prepared starting the corresponding
monomers, which are often proprietary in nature and hence sourcing
those polymers commercially bring other issues. Hence, there is a need
for developing spray-able type liquid-based materials preferably by using
common polymers or such polymers with required modifications etc that
cures at ambient temperature. This would let the vibrating parts of the
machines with complex shapes etc to be spray coated without employing
any arrangement for heat treatment for curing and noise attenuation
could be achieved. Also, there is a further need to develop such materials
with appropriate modifications etc, in a manner that the noise and
vibration could be minimized with structures or coated layers even with
relatively low level of thickness, i.e., in the range of 1 - 3 mm.
As would be explained in detail herein below, the present invention
provides processing and manufacturing of a liquid-based, spray-able
type, filler-modified epoxy resin (Diglycidyl ether bis-phenol A), hardener
(Triethylene-tetramine) based composite paint material for the purpose of

noise and vibration damping, besides environmental protection of
corrosion and usual aesthetics. The invention also provides how the
modulus of elasticity (MOE) of the epoxy resin could be altered, both in
positive and negative directions by incorporating suitable filler material/s
to the blank epoxy resin. The invention would further demonstrate how to
generate the so-called 'bi-layer composite structure' on noise generating
parts of identified machineries by spraying and curing a 'base coat' and a
'top coat' respectively with dissimilar MOE profiles within the filler-
modified materials with an objective to maximize the noise attenuation
those associated with relatively lower level of thickness of coating. These
and other advantages of the invention, i.e., choice of commercial grade
liquid-based two-component epoxy resin polymeric system, incorporation
of the identified filler materials, ambient temperature curing of the
composite paints etc would be apparent from the discussion and
descriptions in the subsequent sections.
ORJECTS OF THE INVENTION:
An object of the present invention is to propose a Filler-modified Epoxy
Resin Hardener Composite Paints for Acoustic Attenuation and a method to
prepare filter-modified commercial-grade epoxy resin (Diglycidyl ether bis-
phenol A) and hardener (Triethylene - tetramine) based composite
materials for the purpose of acoustic attenuation and vibration damping.

Another object of the present invention is to incorporate various pre-
defined solid filler material/s and further to generate various filler-modified
epoxy resin-based composite materials with variable levels of modulus of
elasticity (MOE) in the said composites.
Further object of the present invention is to propose a method to
generate various 'bi-layer composite structure/s' of the derived composite
materials by choosing one composite material as a 'base coat' and
another composite material as a 'top coat' respectively on the basis of
differential levels of MOE.
Yet another object of the invention is to propose a method to specify
typical combinations of 'bi-layer composite structures' those are
associated with superior acoustic attenuation characteristics within
numerous possible combinations of 'bi-layer composite structures' of the
derived composite materials.
Those and further objects of the invention would be understood by
accomplishing various examples and process demonstrations in the
subsequent sections.

BRIEF DESCRIPTION OF THE INVENTION:
According to this invention there is provided spray-able type filler
modified epoxy resin hardener composite paints comprising solid filler
material, liquid epoxy resin, and a liquid hardener material in the range of
1:4:1 - 3:4:1 respectively. A method for preparing a spray-able type filler
modified epoxy resin hardener composite paint comprising mixing the
filler material and the liquid epoxy resin using ball mill machine for a
period of 4 to 8 hours, to form filler modified epoxy materials, mixing the
said filler modified epoxy resin materials with liquid hardener material to
form spray-able type filler modified epoxy composite materials,
subjecting the filler modified epoxy composite materials to the step of
casting and curing, evaluating the modulus of elasticity (MOE) of the
derived "filler modified composite materials", coating the filler modified
epoxy composite materials in bi-layer composite structures on the
surfaces of any target machine, curing the coated layer under ambient
temperature, pressure and humidity.
DETAILED DESCRIPTION OF THE INVENTION:
A process along with its parameters for the preparation of spray-able type
filler-modified epoxy resin-hardener based composite paints for the
purpose of acoustic attenuation. The said composite paint comprises a

commercial-grade liquid epoxy resin (Diglycidyl ether bis-phenol A), pre-
defined filler material/s and a hardener (Triethylene-tetramine)
respectively. The composite paint could be prepared by mixing and
dispersing the filler material/s in the liquid blank epoxy resin followed by
mixing with the hardener, thereby maintaining the appropriate level of
'Resin-Hardener-Filler' ratio in the paint formulations.
The filler-modified epoxy resin-based liquid composite materials are used
in the form of surface coating in the vibrating or acoustic generating
objects or parts by maintaining the desired level of thickness of the
coated layer.
Such coated layer could be generated either by using a single composite
material or in combination of two composite materials with a gradient in
MOE value of the materials. A thickness in the range of 1 - 3 mm is often
preferred when the said material is also used as a protective coating for
erosion or corrosion or aesthetics etc., since a higher level of thickness
would limit the aesthetics though a higher thickness would be advantages
for acoustic attenuation and vibration damping.

The preparation of filler-modified epoxy resin-based liquid composite
materials by incorporating suitable filler material/s in the commercial-
grade liquid epoxy resin, comprise the following steps:
• Mixing and dispersing the two materials, i.e., the filler material/s and
the liquid epoxy resin in a suitable container by using a ball mill
machine for a period of 4 - 8 hours under defined experimental
conditions for generating various filler-modified epoxy resin composite
materials
• Mixing, and dispersing the resultant filler-modified epoxy resin
composite materials with the hardener material for a period of another
15-30 minutes to form hardener-mixed filler-modified epoxy resin
composite materials
• Casting and curing the hardener-mixed filler-modified epoxy resin
composite materials into a solid material under natural conditions and
ambient temperature, pressure and humidity etc.
• Measuring modulus of elasticity (MOE) of the derived filler-modified
epoxy resin composite solid materials
• Generating various 'bi-layer composite structures' by selecting the

'hardener-mixed filler-modified epoxy resin composite materials' those
associated with lower levels of MOE as 'base coat' and other
composite materials with higher levels of MOE as 'top coat' within the
generated composite materials
• Evaluating the acoustic attenuation characteristics of the generated
'bi-layer composite structures' of various filler-modified epoxy
composite materials in a 'ceramic tile cutting blade wheel' machine by
coating the 'cutting blade Wheel' with comparable levels of thickness
in the bi-layer composite structure
• Establishing the complete process of thus-derived filler-modified
epoxy resin based composite materials with various combinations of
'bi-layer composite structures' for the purpose of acoustic attenuation
and vibration damping.
The present invention refers to preparation of spray-able type liquid-
based filler-modified epoxy resin (Diglycidyl ether bis-phenol A) and
hardener (Triethylene-tetramine) composite materials for the purpose of
acoustic attenuation. The composite materials are prepared by
incorporating suitable filler material/s in the commercial-grade epoxy

resin-hardener system. The derived materials in isolation or in
combination could be used for the purpose of acoustic attenuation and
vibration damping. The derived composite materials could be applied on
the surface of various vibrating objects or parts (that contribute to noise
generation), by coating or by spraying the material with desired level of
thickness and then by natural curing the material with the help of a
hardener that cures at ambient temperature, pressure, humidity
conditions etc.
According to the present invention and in order to accomplish the above
objects, there is provided a process for incorporating pre-defined filler
material/s into the commercial-grade epoxy resin for the preparation of
filler-modified epoxy resin composite materials in the form of spray-able
type liquid paints. The filler-modified epoxy resin composite paints are
prepared by incorporating variable amounts of different filler materials in
the range of 20 -60 weight percentage into the epoxy resin system, so as
to generate numerous types of filler-modified epoxy resin composite
materials, all of which are associated with variable levels of modulus of
elasticity (MOE) in the said composites.

In a more particular embodiment of the present invention, the filler
materials are defined as i) melamine powder (C3H6N6) and ii) barium
sulphate (BaS04) respectively. As stated, the incorporation of the said
filler materials in the commercial-grade epoxy resin would generate
various composite materials with variable levels of MOE in the
composites. Table 1 presents the MOE levels of some representative
filler-modified epoxy composite materials.
As per the invention, desired amounts (in volume parts) of epoxy resin
(Diglycidyl ether bis-phenol A) and the filler materials, i.e., melamine
powder and barium sulphate powder respectively are to be mixed
separately and milled by using a ball mill machine or a suitable
mixing/milling machine for a period of 4 - 8 hours in order to get
homogenized filler-mixed epoxy resin materials. To this filler-mixed epoxy
resin, an appropriate amount of hardener (Triethylene-tetramine)
depending on the proportion of the epoxy resin is to be mixed and
thereafter milling operation by ball mill is to be continued for a period of
another 15-30 minutes, after which spray-able type filler-modified
composite paint material would result.

For the purpose of evaluating the MOE profile of the resultant filler-
modified epoxy resin, the material is to be casted in the form of blocks
with desired dimension and to be cured naturally at ambient temperature,
pressure and humidity etc for a period of 15 - 20 hours. After curing, the
material turns into a solid structure, which is used for measuring MOE of
the materials. The Table 1 shows how MOE level of blank epoxy resin
could be altered in the resultant filler-modified epoxy resin composite
materials, by suitably incorporating the filler materials into the epoxy
resin-hardener system.
For the purpose noise attenuation and vibration damping, the filler-
modified epoxy resin composite material could be allied or coated by
spraying or brushing the material on the surface of the vibrating parts or
objects of any target or any identified machine. In case of spray coating,
any standard spray gun could be used by maintaining a corresponding
pressure of 70 - 80 psi and layers of the composite materials could be
generated on the surface of the target object or parts. However, such
coated layers could consist either a single composite material or a
combination of two composite materials as per the Table 1 or outside the
Table 1, just by varying the filler amount in the epoxy-hardener system.
Hence Table 1 presents only certain representative filler-modified epoxy

resin based composite materials. The spraying process could be
repeated in order to eliminate surface voids or defects of the spray-coated
layer and also to generate higher level of thickness.
Hence, various 'bi-layer composite structure' could be generated by
selecting any two composite materials on the basis of differential MOE
using Table 1. The layer which is coated directly to the surface of the
vibrating or noise generating structure or part is called 'base coat' and the
layer above this 'base coat' is called 'top coat'. The 'top coat' is usually
generated after the curing of the' 'base coat' layer. The composite material
belonging to such 'base coat' is associated with lower level of MOE as
compare to that of the 'top coat' which has relative higher level of MOE in
this tri-component 'epoxy resin-hardener-filler' system.
The noise attenuation and vibration damping for each bi-layer composite
structure could be evaluated by identifying certain industrial machine and
the effectiveness of noise attenuation involving such bi-layer composite
structure could be realized. By this process, the 'bi-layer composite
structure' that is more effective for noise attenuation and vibration
damping could also be realized.

In order to accomplish the noise attenuation characteristics of various 'bi-
layer composite structures' of the derived materials, one industrial
machine, i.e., ceramic tile cutting blade wheel (which is made of stainless
steel with a thickness of 2.54 ± 0.05 mm), which is operated by an
electric motor with rpm about 2800 was chosen. It was also realized that
the metallic blade wheel is a vibrating part in the identified machine for
generating the noise while cutting the ceramic tiles. Since the blade
wheel has two sides, the 'bi-layer composite structure' was generated on
the surface of the said wheel in both the sides by spraying the identified
'base coat' and 'top coat', respectively.
In order to understand the effectiveness of the bi-layer composite
structure/s for noise attenuation characteristics, the measurements were
carried out in both 'un-coated (blank)' and 'coated with 'bi-layer composite
structure' conditions in the blade wheel. All the noise level measurements
of the blade wheel (while cutting the ceramic tiles) were carried out under
identical conditions. It has been observed that the noise attenuation is
more effective, as the difference in MOE increases in the bi-layer
composite structure.
The process could be more realized by citing more examples which are
brought out in the following sections.

Example 1:
The 'base coat', which is termed as 'EPM20' was prepared as per
following procedure in this example:
80 volume parts of epoxy resin '(Diglycidyl Ether bis-phenol A) was mixed
with 20 weight percentage of melamine (C3H6N6) filler material in a plastic
container and allowed to be milled (dispersed) for a period of about 4
hours in a standard 'ball mill machine' using ceramic balls as the
mixing/grinding media and by maintaining a rpm of 80, after which a
'melamine-modified epoxy resin' resulted. To this 'filler-mixed epoxy
resin', 20 volume parts of hardener (Triethylene-tetramine) was added
and mixing operation was continued for a period another 20 minutes that
results a spray-able type 'melamine-modified epoxy resin paint' and this
preparation is regarded as the 'base coat' (EPM20) in this example. This
'base coat' preparation, when casted in the form of blocks with
dimensions of about 100 x 30 x 10 mm in the cured state showed a MOE
value of 3.12 GPa.
In order to prepare the 'top coat' in this example, 80 volume parts of
epoxy resin (Diglycidyl Ether bis-phenol A) was mixed and milled with 60
weight percentage of barium sulphate (BaS04) filler material in a plastic
container

for a period of about 4 hours in a standard a 'ball mill machine' using
ceramic balls as mixing/grinding media with a counter rpm of about 80 in
the machine, after which a 'barium sulphate modified epoxy resin'
resulted. To this preparation, about 20 volume parts of hardener
(Triethylene-tetramine) was added and mixing operation was continued
for another period of 20 minutes that results a barium sulphate-modified
epoxy resin paint' and this preparation is regarded as the 'top coat' and
termed as 'EPB 60' in this example. This 'top coat' preparation, when
casted in the form of blocks with dimensions of about 100 x 30 x 10 mm
in the cured state showed a MOE value of 4.61 GPa.
The 'base coat' (EPM20) was sprayed on the surface of the ceramic tile
cutting wheel blade (which is made of stainless steel with a thickness of
2.54 ± 0.05 mm) on both the sides by using a spray gun and by
maintaining the pressure level of about 70 psi and then cured under
natural conditions of temperature, pressure and humidity etc. The
spraying operation was continued until a thickness profile of 0.6 ± 0.05
mm resulted after curing, which accounts about 0.3 mm in each side of
the blade wheel.

The 'top coat' (EPB 60) was then sprayed on the surface of the cured
layer of the base coat of ceramic tile cutting wheel blade on both the
sides by using a spray gun and by maintaining the pressure level of about
70 psi and thereby cured under natural conditions. The total thickness
after the curing resulted to 1.6 ± 0.05 mm, which accounts about 0.8 ±
0.05 mm in each side together the base and the top coat respectively.
Ceramic tile (alumina ceramic tile with density of about 3.3 ± 0.05 g/cc)
was chosen for evaluating the noise attenuation characteristics of the
cutting wheel blade. The blade wheel was operated by an electric motor
with rpm of about for cutting the ceramic tiles. The 'A-weighted noise
levels' of both 'LAeq(dB)' and 'LAFmax(dB)' were recorded by maintaining
identical conditions of ceramic tile cutting operation in both 'blank (un-
coated)' and 'bi-layer composite structure coated' conditions of the blade
wheel, by following IEC 61672-2:2006 noise measurement standard.
The 'LAeq(dB)' noise level of the blade wheel (blank or un-coated
conditions) during operation is 87.7 ±1 dB and to that of 'coated bi-layer
composite structure' is 83.1 ± 1 dB respectively. This example
demonstrates the noise reduction of about 4.1 ±1 dB for the blade
wheel,

which is associated with this specific 'bi-layer composite structure' in with
a thickness of about 1.61 ± 0.05 mm.
Example 2:
The 'base coat', which is termed as 'EPM40' was prepared as per
following procedure in this example:
80 volume parts of epoxy resin (Diglycidyl Ether bis-phenol A) was mixed
with 40 weight percentage of melamine filler material in a plastic container
and allowed to be milled (dispersed) for a period of about 4 hours in a
standard 'ball mill machine' using ceramic balls as the mixing/grinding
media and by maintaining a rpm of 80, after which a 'melamine-modified
epoxy resin' resulted. To this 'filler-mixed epoxy resin', 20 volume parts of
hardener (Triethylene-tetramine) was added and mixing operation was
continued for a period another 20 minutes that results a spray-able type
'melamine-modified epoxy resin paint' and this preparation is regarded as
the 'base coat' (EPM40) in this example. This 'base coat' preparation,
when casted in the form of blocks with dimensions of about 100 x 30 x 10
mm in the cured state showed a MOE value of 2.55 GPa.

The preparation of the 'top coat' in this example remains the same to that
of Example 1 and hence of MOE value remains the same.
The coating procedure and creating 'bi-layer composite structure'
remained the same to that of Example 1. The thickness profile of 'base
coat' (EPB60) in this example was 0.7 ± 0.05 mm that accounts 0.35 ±
0.05 mm in each side of the blade wheel. The total thickness after the
curing the 'top coat' resulted to 1.46 ± 0.05 mm, which accounts about
0.73 ± 0.05 mm in each side together the base and the top coat
respectively.
Similar types of ceramic tile (alumina ceramic tile with density of about
3.3 ± 0.05 g/cc) was chosen for evaluating the noise attenuation
characteristics of the cutting wheel blade and the operation conditions
remained the same for cutting the ceramic tiles. The 'A-weighted noise
levels' of both 'LAeq(dB)' and 'LAFmax(dB)' were recorded by maintaining
identical conditions of ceramic tile cutting operation in both 'blank (un-
coated)' and 'bi-layer composite structure coated' conditions of the blade
wheel, by following I EC 61672-2:2006 noise measurement standard.

The 'LAeq(dB)' noise level of the blade wheel (blank or un-coated
conditions) during operation is 87.2 ± 1 dB and to that of 'coated bi-layer
composite structure' is 82.9 ± 1 dB respectively. This example
demonstrates the noise reduction of about 4.3 ± 1 dB for the blade wheel,
which is associated with this specific 'bi-layer composite structure' in with
a thickness of about 1.46 ± 0.05 mm.
Example 3:
The 'base coat', which is termed as 'EPM60' was prepared as per
following procedure in this example:
80 volume parts of epoxy resin (Diglycidyl Ether bis-phenol A) was mixed
with 60 weight percentage of melamine filler material in a plastic container
and allowed to be milled for a period of about 4 hours in a standard 'ball
mill machine' using ceramic balls as the mixing/grinding media and by
maintaining a rpm of 80, after which a 'melamine-modified epoxy resin'
resulted. To this 'filler-mixed epoxy resin', 20 volume parts of hardener
(Triethylene-tetramine) was added and mixing operation was continued
for a period another 20 minutes that results a spray-able type 'melamine-
modified epoxy resin paint' and this preparation is regarded as the 'base
coat' in this example. This 'base coat' (EPM60) preparation,

when casted in the form of blocks with dimensions of about 100 x 30 x 10
mm in the cured state showed a MOE value of 2.34 GPa.
The preparation of the 'top coat' (EPB60) in this example remains the
same to that of Example 1 and hence the MOE remains the same here as
well.
The coating procedure and creating 'bi-layer composite structure'
remained the same to that of Example 1. The thickness profile of 'base
coat' in this example was 0.7 ± 0.05 mm that accounts 0.35 ± 0.05 mm in
each side of the blade wheel. The total thickness after the curing the 'top
coat' resulted to 1.48 ± 0.05 mm, which accounts about 0.74 ± 0.05 mm in
each side together the base and the top coat respectively.
Similar types of ceramic tile (aJumina ceramic tile with density of about
3.3 ± 0.05 g/cc) was chosen for evaluating the noise attenuation
characteristics of the cutting wheel blade and the operation conditions
remained the same for cutting the ceramic tiles. The 'A-weighted noise
levels' for both 'LAeq(dB)' and 'LAFmax(dB)' were recorded by
maintaining identical conditions of ceramic tile cutting operation in both
'blank (un-coated)' and 'bi-layer composite structure coated' conditions of

the blade wheel, by following EC 61672-2:2006 noise measurement
standard. However, only 'LAeq(dB)' values have been considered in each
case for comparison from one 'bi-layer composite structure* to another
structure.
The 'LAeq(dB)' noise level of the blade wheel (blank or un-coated
conditions) during operation is 87.2 ± 1 dB and to that of 'coated bi-layer
composite structure' is 82.6 ± 1 dB respectively. This example
demonstrates the noise reduction of about 4.6 ± 1 dB for the blade wheel,
which is associated with this specific 'bi-layer composite structure' in with
a thickness of about 1.48 ± 0.05 mm.
Table 2 demonstrates the summary of the of noise damping
characteristics of various bi-layer composite structures by taking a typical
industrial ceramic cutting blade wheel operation as an example, noise
attenuation of which has been generated by maintaining under identical
conditions of operation.
Therefore, the acoustic attenuation characteristics of the aforesaid filler-
modified epoxy resin based composite paints by coating such materials
on noise generating surfaces with typical bi-layer composite

structures is established in this invention.
Table 1: Chemical Formulations and Modulus of Elasticity (MOE)
Profiles of the Filler-modified Epoxy Resin Composite Materials


Table 2: Noise Attenuation Characteristics of 'Bi-layer Composite
Structures' of Filler-modified Epoxy Resin Composite Paints in a typical
industrial machine, i.e., 'Ceramic Tile Cutting Blade Wheel Operation'


We Claim:
1. Spray-able type filler modified epoxy resin hardener composite
paints comprising solid filler material, liquid epoxy resin, and a
liquid hardener material in the range of 1:4:1 - 3:4:1
respectively.
2. A method for preparing a spray able type filler modified epoxy
resin hardener composite paint comprising mixing the filler
material and the liquid epoxy resin using ball mill machine for a
period of 4 to 8 hours, to form filler modified epoxy materials,
mixing the said filler modified epoxy materials with liquid
hardener material to form spray-able type filler modified epoxy
composite materials,
subjecting the filler modified epoxy composite materials to the
step of casting and curing, evaluating the modulus of elasticity
(MOE) of the derived "filler modified composite materials"
coating the filler modified epoxy composite materials in bi-layer
composite structures on the surfaces of any target machine
curing the coated layer under ambient temperature, pressure
and humidity.

3. The method as claimed in claim 2, wherein the said filler
modified epoxy material in mixed with liquid hardener material
for a period of 15 - 30 minutes.
4. The method as claimed in claim 2, wherein filler modified epoxy
composite material is treated as a "base coat" depending on the
level of MOE.

5. The method as claimed in claim 4 wherein the filler material used to
lower MOE is melamine powder (C3H6N6) and for enhancing the MOE
is barium sulphate.
6. The method as claimed in claim 2 wherein the said bi-layer composite
structure comprises of 60% of melamine filler load as the "base coat
and barium sulphate filler as the "topcoat" to maximize acoustic
attenuation effect